A vehicle enables transportation on the road using fossil fuel and electricity as power sources.
Recently, it has been common for the vehicle to include an audio device and a video device to allow a driver to listen to music and to watch videos, as well as to simply transport cargo and people. Further, a navigation system has been widely installed in vehicles to display a route to a destination that is desired by the driver.
Recently, there is a growing need for the vehicle to communicate with an external device. For example, in the case of a navigation function to guide the route to the destination, information about the traffic conditions of the road is required to find the optimal route. Since the traffic conditions frequently change, it may be required for the vehicle to acquire the information about the traffic conditions in real time.
In addition the system for driver's safety has been actively developed, e.g. Forward Collision Warning System (FCWS) and Autonomous Emergency Braking (AEB) for ensuring the safety of the driver and for providing convenience of the driver. The Forward Collision Warning System (FCWS) and Autonomous Emergency Braking (AEB) may estimate whether a collision with a proceeding vehicle is likely and a collision estimated time based on location information of the proceeding vehicle detected by a radar device.
A communication device for communication with the external device and a radar device for the forward collision warning includes an antenna configured to send and receive radio waves.
A car antenna technology currently on the market is limited to a patch antenna array. This is because it is possible to implement a light weight and a thin antenna in such an array. However, for the patch array antenna, there may be a dielectric loss caused by the use of a dielectric substrate and thus the performance of the antenna is significantly reduced due to the dielectric loss. In particular, in 5G communication technology or the radar using several tens of GHz or more as a high frequency, the efficiency of the patch antenna is less than 30%. In addition, the patch array antenna uses a feeding structure in series and thus the patch array antenna has an extremely narrow frequency band characteristic.